NutraIngredients -- Supplementation with a yeast fermentate can boost the immune system and reduce the occurrence of cold and flu symptoms by 21 per cent, according to the results of randomised clinical trial. Amongst the 116 people who took part in the study, those who did have symptoms experienced a reduction in the duration by 14 per cent after receiving supplements of Embria's EpiCor yeast fermentate, reports the study in the journal Urologic Nursing.